The effective transport of research-based interventions to community-based practice is a public health priority. To address this priority for youth with substance use problems, treatment and transportability strategies must address four major challenges. (1) Concerns about the extent to which treatment outcomes achieved under controlled conditions in efficacy trials can be achieved under usual care conditions. (2) The comorbidity of psychiatric disorders, particularly conduct and other disruptive behavior disorders with youth drug abuse. (3) Barriers to the adoption and implementation of empirically supported treatments arise at multiple levels of the service context. (4) Problems with the nation's substance abuse service infrastructure suggest other systems should be enlisted to meet the needs of youth with drug problems. This application proposes secondary analyses to leverage the 2.5 million research dollars and 15.6 million service dollars expended in a 41-site, NIMH-funded study of the transportability of an empirically supported treatment to 1950 youth with serious antisocial behavior, 415 of which have comorbid drug use problems. The design of that study, proposed collection of one additional year of follow-up data, and proposed secondary data analyses will enable us to address the aforementioned concerns by accomplishing three aims. Aim 1: Using a benchmarking strategy, compare the drug-related crime and general criminal outcomes through 2 years post-treatment of Transportability sample youths with co-occurring antisocial and substance use problems and the 2-year post-treatment outcomes achieved among such youths in randomized clinical trials of MST; and, compare the behavior problem, psychosocial functioning, and drug-related and general criminal outcomes through 1 year post-treatment in the Transportability and RCT samples. Aim 2. To compare, within the Transportability sample, drug-related and general criminal outcomes 2 years post-treatment among youths with and without identified drug use problems; and, to compare 1 year post-treatment behavior problem, psychosocial functioning, and substance use problems of these two groups. Aim 3: Test a multivariate contextual model of treatment implementation and outcomes for youth with antisocial behavior with and without substance use problems. 3a. To examine the influence of system-level variables (referral and reimbursement source and type), organizational structure and climate, therapist adherence, and other therapist variables (training, experience, education) on treatment outcomes for youth with and without substance use problems. 3b. To examine the influence of referral and reimbursement source and type, organizational structure and climate, and therapist variables on therapist adherence when treating youth with and without substance use problems. 3c. To examine therapist adherence to MST for youths with and without substance use problems. Together, these analyses will test the proposition that certain treatment and transport strategies, if sufficiently comprehensive, can improve community-based care for youth with substance use problems outside of specialty substance abuse clinics.